The invention broadly relates to telecommunications and more particularly relates to improvements in digital subscriber line networks.
There are several forms of the Digital Subscriber Line protocol, referred to collectively as xe2x80x9cxDSLxe2x80x9d. They have the common feature of operating at high bit rates and with a high reliability over existing twisted pair copper lines. xDSL makes full use of the copper line frequency spectrum of approximately 2 MHz, it uses advanced modulation and coding methods, and it works simultaneously with the plain old telephone system (POTS) on the same copper line.
Twisted pair copper lines have a useable frequency spectrum of approximately 2 MHz, which depending on the length of the line, can be used for data communication at various bit rates. However, there are two limitations: first, the lower 4 kHz must be reserved for POTS signals where applicable, and second, the signal to noise ratio is not the same in all frequencies.
Discrete MultiTone (DMT) is a modulation technique used in xDSL technologies, that divides the frequency range into 256 sub-frequencies, from 64 kHz to 2 MHz. Each sub-frequency is an independent channel which has its own stream of signals . Asymmetric Digital Subscriber Line (ADSL) protocol, one of the family of xDSL protocols, defines a pilot stream of data which is known to both endpoints in advance. This pilot stream of data is transmitted on each sub-frequency to enable the endpoints to find the specific signal to noise ratio (SNR) for each sub-frequency. This information is used to allocate the data over the various sub-frequencies. The POTS signals in the lower 4 kHz band are separated by an analog splitter, thereby enabling telephone voice calls to simultaneously share the twisted pair copper line with ADSL digital signals. ADSL is asymmetric in its allocation of more bandwidth to the downstream signals from the network to the customer, compared with less bandwidth in the upstream direction.
The various forms of digital subscriber line (xDSL) technologies are known under the acronyms ADSL, HDSL, RADSL, SDSL, and VDSL. Their principal characteristics are reviewed as follows:
ADSL: Asymmetric digital subscriber line (ADSL) protocol is a passband modulation of coded information bit streams over the POTS twisted-pair two-wire telephony copper loop. This protocol uses two-dimensional modulation schemes such as carrierless amplitude-phase (CAP) or discrete multi-tone (DMT). Carrierless amplitude phase modulation (CAP) is a version of quadrature amplitude modulation (QAM) that stores parts of a modulated message signal in memory and then reassembles the parts in the modulated wave. The carrier signal is suppressed before transmission because it contains no information and is reassembled at the receiving modem (hence the word xe2x80x9ccarrierlessxe2x80x9d in CAP). Commercially available ADSL modems are capable of transmitting up to 8 Megabits per second (Mbps) downstream in the 240 kHz to 2 MHz loop frequency band and up to 1 Mbps upstream in the 25 kHz-200 kHz spectral band, simultaneously with 0-4 kHz telephony (POTS) signals. State-of-the-art ADSL modems typically employ rate-adaptation, with a granularity (e.g., 32 kbps for DMT and 320 kbps for CAP in current implementations) to increase or decrease the transmitted bit rate automatically in response to variations in loop noise conditions and loop lengths. The ADSL standard is described in American National Standards Institute (ANSI) standard T1.413, entitled xe2x80x9cTelecommunications-Network and Customer installation Interfaces-Asymmetric Digital Subscriber Line (ADSL) Metallic Interfacexe2x80x9d, (ADSL 6.1 Mbps).
HDSL: High-data-rate DSL (HDSL) is a four-wire (two-pair) access protocol for achieving symmetrical data transmission rates, conforming to either the T1 (1.544 Mbps) or E1 (2.048 Mbps) standards, using either baseband the ISDN encoding technique of two binary, one quaternary (2B1Q)or passband CAP (e.g., CAP64) modulation schemes. Fractional T1 or E1 rates are supported by most HDSL modem vendors using nxc3x9764 kbps clocking schemes. The HDSL spectrum in the copper loop extends approximately between 0-300 kHz for passband modulated-transmission (e.g., CAP64) and 0-425 kHz for baseband 2B1Q) modulated data transmission. In practice, commercially-available HDSL modems (specifically the baseband 2B1Q HDSL modems), do not support simultaneous transport of analog telephony and the HDSL modulated data signals.
RADSL: Rate-adaptive digital subscriber line (RADSL) adjusts transmission speed according to the length and quality of the local line. Connection speed is established when the line is initially synchronized or is set by a signal from the central office. This is similar to CCITT standard V.34 modems, which initialize communications with one another by first listing which bit rates they support. Then they go into a test mode to determine which of the supported bit rates is the highest one which can be used for each new connection. RADSL modems poll the line before transmitting and periodically monitor the line speed during a session to determine if it is necessary to change bit rates due to changes in the line condition. If the RADSL modems recognize that they are experiencing a very low error rate over a given time period, they can agree to go to a higher bit rate. Alternatively, they can go to a lower bit rate if line conditions indicate that too many errors have occurred during some period.
SDSL: Symmetric DSL (SDSL) protocol is a two-wire (single-pair) implementation of the ISDN encoding technique of two binary, one quaternary (2B1Q) or of the CAP modem technologies using state-of-the-art echo-cancellation and adaptive-equalization techniques. This achieves symmetric data transmission rates of 384 kbps, 768 kbps, 1 Mbps, 1.5 Mbps, or 2 Mbps . Sub-T1/E1 rates can be obtained using nxc3x9764 kbps clocking techniques.
VDSL: Very-high-speed DSL protocol supports data transmission rates of 6.5 Mbps to 51.8 Mbps (the Synchronous Optical Network OC-1 rate) downstream and 1.6 Mbps to 6.5 Mbps upstream, for asymmetrical services. VDSL protocol supports data transmission rates of 6.5 Mbps to 25.9 Mbps for symmetrical services, over short two-wire loops (typically around 1 kft). Candidate modulation schemes proposed for VDSL include M-ary CAP, M-ary quadrature amplitude modulation (QAM) and DMT.
Although xDSL technologies offer the advantage of high data rates over the ubiquitous, twisted pair POTS lines, there remain areas needing improvement. One area needing improvement is in the lack of control by the customer or by the system administrator over the privileges and features, referred to in telephone parlance as the xe2x80x9cclass of servicexe2x80x9d, of the customer""s xDSL connection to the digital network. A primary component of the customer""s class of service is the data rate of the customer""s data communication session. A customer does not need, and should not have to pay for, a megabit per second data rate when sending email over the Internet. However, that same customer will require a megabit per second data rate when receiving streaming data, such as full motion digital video, over the Internet. What is needed is a way for a customer or network administrator with a web-based interface to change the class of service of the customer""s xDSL connection to the digital network, referred to in telephone parlance as the customer""s xe2x80x9clocal loopxe2x80x9d. What is needed is for a customer or network administrator to be able to request an immediate change in the bit rate during the customer""s xDSL session. What is needed is for the customer to be able to subscribe to a service plan that automatically changes the bit rate of the customer""s xDSL local loop, depending on the customer""s usage or the type of data traffic occurring during a session. What is needed is for a customer or network administrator to be able to define a schedule that is followed to automatically change the bit rate of the customer""s xDSL loop based on the time of the day, the day of the week, or other schedulable factors. What is needed is for a customer or network administrator to be able to select an option to automatically increase the bit rate of an xDSL loop when receiving streaming video or audio content from the Internet.
A server platform communicates with a plurality of customer digital subscriber line modems at customer sites and also communicates with an Internet service provider connected to the Internet. The server platform includes a plurality of platform digital subscriber line modems, each respectively connected to a customer digital subscriber line modem. The platform includes an Ethernet local area network (LAN) that is coupled to each of the platform digital subscriber line modems. A web server is coupled to the Ethernet LAN, and is coupled to the Internet. Customers communicate with websites on the Internet through the server platform.
In accordance with the invention, the web server in the server platform is programmed to receive requests from the customer digital subscriber line modems for changing the customer""s class of service for access to the Internet. The server platform can provide an immediate change in the bit rate of a platform digital subscriber line modem in response to a customer""s request. The server platform can provide a service plan that automatically changes the bit rate of a platform digital subscriber line modem in response to a customer""s request. The server platform can selectively provide a schedule that is followed to automatically change the bit rate of a platform digital subscriber line modem in response to a customer""s request. In addition, the server platform can selectively provide an option to automatically increase the bit rate of a platform digital subscriber line modem when receiving streaming video or audio content from the Internet. A database is coupled to the Ethernet LAN to store the class of service status of each respective platform digital subscriber line modem.
When a customer requests from the customer digital subscriber line modem, changing the customer""s class of service for access to the Internet, the platform digital subscriber line modem causes an Ethernet packet containing the request, to be addressed to the web server. In response, the web server can grant the customer""s request and record it in the database. An SNMP network manager coupled to the Ethernet LAN identifies the recorded request on the database and in response, forms a control message that is sent to the respective platform digital subscriber line modem that is coupled to the customer""s modem. The control message changes the class of service provided by the platform digital subscriber line modem to conform with the customer""s request. This mode of operation of the server platform is used to provide an immediate change in the bit rate, to provide a service plan that automatically changes the bit rate of a platform digital subscriber line modem, and to provide a schedule that is followed to automatically change the bit rate of a platform digital subscriber line modem.
The server platform includes an HTTP gateway that couples the server platform to the Internet. The gateway monitors HTTP packets received from the Internet and identifies streaming data packets that require a higher bit rate. In response to detecting the streaming packets, the HTTP gateway sends an HTTP response header field to the web server. The web server prepares an SNMP set request message specifying a high bit rate, and stores the message in the database. The web server then sends the SNMP Set Request message to the SNMP controller, which forms an Ethernet frame containing the message and sends it to the platform modem. The controller sends the control message in an Ethernet frame to the platform xDSL modem addressed by the HTTP packet, to change its bit rate. This mode of operation enables the server platform to automatically increase the bit rate of a platform xDSL modem when receiving streaming video or audio content from the Internet network.